Polytetrafluoroethylene

Polytetrafluoroethylene has the trade name Teflon Virgin PTFE is a white, waxy-feeling industrial material that is practically chemically resistant. It’s a tetrafluoroethylene-derived synthetic fluoropolymer. It’s a fluorocarbon molecule with a high molecular weight that’s solid. Fluorine and carbon make up the majority of it.

 It is hydrophobic, it cannot be made wet by water or water-containing chemicals. Fluorine’s high electro-negativity and low friction coefficients against many types of materials make this achievable, and only a few substances react with it. It has a high oxygen index and excellent chemical resistance. It is unaffected by practically all substances. It has a less friction coefficient  and is stable at high temperatures.

Polytetrafluorethylene structure

Polytetrafluoroethylene has a chemical structure similar to polyethylene (PE), but the hydrogen atoms have been replaced by fluorine (hence it is referred to as perfluoro polymer)

It’s the size of a fluorine atom, and it forms a homogeneous and continuous sheath surrounding carbon-carbon bonds, giving the molecule chemical resistance and stability. The molecule is also electrically inert due to the fluorine sheath’s uniformity. Polytetrafluoroethylene has a theoretical fluorine concentration of 76 percent and a crystallinity of 95 percent. 

Properties of polytetrafluoroethylene

• • ·         At room temperature, polytetrafluoroethylene is a white solid with a density of around 2.2 g/cm3.
  • ·         The coefficient of friction is 0.1 or less, the lowest of any solid substance known.
  • ·         Its resistance to van der Waals forces, PTFE is the only surface on which a gecko cannot adhere.
  • ·         The dielectric characteristics of PTFE are outstanding, making it an ideal insulator for use in cables and connector assemblies.
  • ·         It has a melting point of 327 °C; however, its characteristics deteriorate at temperatures beyond 260 °C.
  • ·         PTFE has a high melting temperature, making it the material of choice as a high-performance replacement for polyethylene.
  • ·         It’s great for making long-life electrets because of its extraordinarily high bulk resistivity.

Process of PTFE making

Teflon is manufactured from four ingredients: fluorspar, hydrofluoric acid, chloroform, and water, mixed in a chemical reaction chamber heated to between 1094- and 1652-degrees Fahrenheit. Polytetrafluoroethylene is made up of two major phases and several reactions.

Trichloromethane, hydrofluoric acid, and fluorspar must be used to make TFE. Pyrolysis is the process of combining these substances. TFE is highly flammable, and transporting it is quite hazardous. As a result, this procedure must be completed on-site at the PTFE manufacturing facility.

TFE polymerization (creating PTFE out of TFE)

While many specifics of the TFE polymerization process are trade secrets of well-known manufacturers, there are two crucial processes for generating PTFE: suspension polymerization and dispersion polymerization.

The first approach produces PTFE grains that may be processed into pellets and then moulded. The latter approach generates PTFE as a milky paste that may be ground into a fine powder.

There are two different procedures used:

1.Suspension polymerization

It produces a 1 cm long suspension of PTFE particles in water.Further processed into fine powders that are utilized in molding. To improve flow, the fine particles are agglomerated into bigger particles. To push the particles to stick together, the powder particles are shaped in the form of a rod for extrusion and heated to temperatures more than 530 K. This is how around a third of the PTFE is made. Prior to the manufacture of sheets and rods, fillers are frequently applied.

2.Dispersion polymerization

Dispersion polymerization is used to obtain a colloidal solution of PTFE particles in water. The dispersion can convert into high viscosity and applied to items via spraying. It can alternatively be coagulated and dried to produce a fine powder that is then turned into a  solvent paste and extruded onto the wire. The wire is widely used in automobiles and aeroplanes when exposed to high temperatures.

 Polytetrafluoroethylene uses

•         Teflon, the most well-known PTFE, is used to produce non-stick cookware.
•         PTFE’s non-stick characteristics are so effective that it can be utilised on building surfaces to keep insects from climbing walls.
•         Polytetrafluoroethylene is used in dentistry to keep fillings from clinging to neighbouring teeth.
•         Because it is anti-corrosive and non-reactive, PTFE is utilised to build containers and pipes.
•         PTFE is a lubricant used in machinery. Friction, energy consumption, and equipment wear are all reduced.
•         Because of its strength and heat resistance, PTFE is used to produce gaskets.
•         To insulate cables and connector assemblies, PTFE is employed.
•         Consumer products containing PTFE include school uniforms, footwear, insoles, and orthotics.

Limitations of PTFE

PTFE, like most polymers, has some drawbacks, including:

•         Radiation resistance is poor.
•         Corrosive
•         Toxic gases might make you sick.
•         Joining difficulties
•         Abrasion sensitivity
•         Around transition temperature, there is a dimensional difference.

These restrictions only apply if the polytetrafluoroethylene is subjected to higher temperatures than mentioned above.

 Recycling of PTFE material

 PTFE waste cannot be disposed of in a landfill or burned. Recycling PTFE entails two distinct processes with two distinct outcomes

•         One method includes exposing the PTFE scrap to a high amount of ionising radiation, which lowers its molecular weight. Pulverising the irradiated PTFE scrap produces micro powder, which can be used in various applications.
•         The second process entails crushing the PTFE debris without exposing it to radiation, allowing it to be reused like fresh PTFE.

Conclusion

Polytetrafluoroethylene is a tetrafluoroethylene fluoropolymer.PTFE is an extraordinarily versatile substance with a vast number of applications, though it’s arguably best-known for its non-stick features. It’s hydrophobic,high density, non-wetting, and resistant to high temperatures.